// 函数组合演示

function compose (f, g) {
    return function (value) {
        return f(g(value))
    }
}

function reverse (array) {
    return array.reverse()
}

function first (array) {
    return array[0]
}

const last = compose(first, reverse)
console.log(last([1, 2, 3, 4]))